Richard E. Rubenstein (1938-) is an author and Professor of Conflict Resolution and Public Affairs at George Mason University, holding degrees from Harvard University, Oxford University, and Harvard Law School. He has written numerous books analyzing periods of violent and non-violent conflicts across human history. He has also been a part of numerous peace movements regarding domestic and international issues in the 1960s and 70s. In Aristotle’s Children, Rubenstein analyzes the reclamation of Aristotelian thought in the Middle Ages, with an emphasis on the response of the Roman Catholic Church.

In the seventh century, both halves of the fractured Roman empire lost touch with their intellectual heritage. These cultural resources had been waning for a couple centuries due to Rome’s loss of political and economic predominance. Alongside the political turmoil of this period, the Catholic Church was developing its ideological and cultural prestige. Numerous church councils across the preceding three centuries generated official church doctrine, as well as ideological rifts between the church and newly minted heretics.

These twin pressures sent refugees of the Roman empire and Christianity to Arab countries. These countries would become Islamic after the rise of Mohammed, leading to a cultural revolution that would dominate the early Middle Ages. Yet within these newly Islamic lands, many influential texts brought by the refugees were preserved and kept safe as barbarian tribes carved up Roman territories.

Significant amongst these texts was a nearly complete corpus of Aristotle’s works, lost to the Christian West but now at home in the Islamic East. These works—covering topics ranging from the soul and ethics to natural science and politics—were translated from Greek into Syriac, Persian, and eventually Arabic for dissemination throughout Islam.

Five long centuries passed, until the crusades in the 11th and 12th centuries led to a great cross-cultural event. In the formerly Islamic city of Toledo, Spain, the church stumbled upon massive libraries containing Greek and Roman texts—chiefly Aristotle’s—that had been missing for half a millennium. Moreover, Christian scholars also encountered a rich tradition of Islamic philosophy borne out of deep reflection upon these preserved texts.

For the first time in several hundred years, the intellectual culture of the West was externally stimulated by both the reclamation of Aristotelian philosophy and the Arab philosophers who had laboriously incorporated, refined, and developed their own philosophical tradition in response to Aristotle. Translation teams representing Greek, Jewish, Islamic, and Christian peoples descended on these libraries to begin the task of disseminating these lost books to the West.

Beginning in Toledo in the early 12th century, this cross-pollination of the intellectual resources of Christendom, Islam, and Judaism set the course for a new phase in human history.

Prior to the initial reclamation of Aristotelian philosophy by Christendom, numerous theologians and monks were applying the tenets of logic to the doctrines of the faith. Though the Christian faith has never rebuked the usage of reason, many Christians had previously valued an understanding of reason as a tool limited by the brokenness of man and the magnificence of God.

The Middle Ages brought an increasing emphasis on the power of rationality to disclose heretofore unknown truths regarding the doctrines of faith. Previously sacrosanct topics such as the Trinity, the Incarnation, and the nature of the Lord’s Supper were now being subjected to the canons of logic and the philosophical tools bequeathed by Aristotle. It was not enough for some to assert these divine mysteries to be real and miraculous, one also had to understand them in human language and concepts.

One notable figure who accelerated this cultural shift was Peter of Abelard. A renowned philosopher, debater, and theologian, Abelard is known for shaking up the burgeoning European university culture with his provocative analysis of Christian doctrine. One notable work of his is called Yes and No. It is a workbook composed of various statements of noted Church Fathers on various topics, many of which contradict each other. Though Abelard composed this text to help his students navigate different arguments and work out the inconsistencies, some saw his work as deliberately inflammatory. Though a Christian through and through, Abelard did intentionally seek to raise doubts so that they could be rationally handled. In the preface to the work, Abelard even calls upon the example of Aristotle, who encouraged his students to doubt, inquire, and by inquiry perceive the truth of a matter.

Though a noble aim, prompting intentional doubt is a risky endeavor when it comes to issues of piety and fidelity to the one true God. Abelard’s work, however, was but a foretaste of things to come as the medieval church began to reconsider its concept of truth, the pursuit of religious knowledge, and how one rightly honors God with one’s mind.

In the beginning of the 13th century, two powerful Christian orders became enmeshed in the University of Paris. In 1217, the Dominicans, who emphasized intellectual rigor and debate against heretics, enrolled as students. The Fransican order emphasized care for the poor and pastoral ministry. They established a presence in Paris two years later. Members of both orders were students and teachers in the university, and soon spread to other major European universities.

The church had imposed a ban on Aristotelian “natural philosophy” for numerous universities in the early 13th century. This was largely a response to heretical sects of Christendom that had armed themselves with Aristotle’s arguments to promote their erroneous doctrines. Despite the official removal of Aristotle from lectures and curricula across Europe, the University of Paris, well known as the center of theological education and research, bore this ban most severely. Maintaining the ban in Paris created a barrier, keeping philosophical practices from endangering the church’s theological traditions. The University of Paris experienced pressure from the ban until the 1230s, when the Dominicans and Franciscans arrived, adopted teaching positions and increasingly emphasized the return of Aristotle to the curricula. Their insistence on studying all of Aristotle’s works led to adoption of Aristotelian thought into the fabric of Catholic orthodoxy, in part because of the orders’ connections to powerful church figures. 

One noted figure during this period was Albert the Great, a Dominican friar noted for both his theological and philosophical insights, as well as his work as a scientist. Botany and zoology were his greatest scientific pursuits, and he collected various species of plant and animal life. Albert’s fascination with the natural world was motivated by his reading and reflection upon Aristotle’s works. Devoted as he was to preserving the faith, he likewise maintained that experience, what we would call empirical research, was the path to certainty in practical matters of knowledge. Rather than mix Aristotle and Christianity, Albert considered empirical, logical, and Scriptural reasoning as distinct forms of inquiry, each with its own method. Albert’s opinions became part of the major debates that would well up in the church.

Despite the earnest approach to Aristotle taken up by Albert and other church scholars, numerous questions arose regarding the intersection of theology, philosophy proper, and natural philosophy (what we presently call science). Could one really treat them all as separate entities? Did each have its own methods, object of study, and clearly defined lines that kept it from the others? It seems that the domains of these disciplines overlapped, with a question poised in philosophy having theological and scientific considerations as well.

For example, consider the origin of the universe. In Aristotle’s philosophical texts, he claims that the universe is uncreated and eternal. Nowadays, thanks to empirical research in the science of astrophysics, the big bang hypothesis interposes an answer that is scientific with inescapable philosophical commitments. Moreover, even in the Middle Ages, theological considerations amongst Christians, Jews, and Muslims prevented them from agreeing with Aristotle. To do so would contradict their Scriptures, which reveal a distinct creator God who formed the universe out of nothing.

More than just presenting queries, investigations and answers, Aristotle’s reintroduction to the church gave budding theologians new conceptual tools and prompted specific issues in their understanding of God. For example, questions arose concerning how God creates and sustains his world. Does God presently create? We may be inclined to say no after reading Genesis 1 and 2, or if we simply believe the world was created a long time ago and now operates on its own. To say the world operates on its own natural causes—like Earth rotating around the sun or plants growing out of seeds—seems to distance God from his creation. Since Christianity teaches that God is providential and sustains creation, this could lead us to believe that the natural world is continually being propped up or renewed by God. Seemingly, the operation of the natural world has both natural and supernatural causes, an idea known at the time as dual causation. 

Questions about dual causation dominated discussion in the Middle Ages. If God is wedded too closely to his Creation as the sole cause, then one risks pantheism, of creation being God. If God is too far from his creation, one has to reconsider the Scriptures that depict him as a sustainer and present Father. As Aristotle’s works became more intertwined with Medieval Christianity, issues such as these brought philosophy and theology into debates like never before in the history of Christendom.

In the second half of the 13th century, a group of radical Aristotelian philosophers at the University of Paris insisted on a division between the truths of theology and philosophy. Previously, the assumption that all truth is God’s truth permeated Christendom broadly and the universities in particular. Though debates had risen about the relevance of Aristotelian thought to Christian doctrine, the common conception of truth at the time was unitary. The radical philosophers in Paris called this into question with a belief that came to be called Double Truth.

This group, led by a scholar named Siger de Brabant, claimed not only that philosophy and theology were distinct fields of inquiry, but also that they each had their own truths that could exist in contradiction to those of the other field. Double Truth meant that something could be true “scientifically” (that is, according to observation or argumentation) while being false theologically (that is, according to Scripture), or vice versa. This position reflected the group’s insistence on Aristotle’s authority and on the use of reason to discover truth. The problem with this position is that it allows for open logical contradictions.

Consider the origin of the world again. Aristotle has philosophical arguments defending the standard Greek view that creation is eternal. Even under experience and observation of the world around us, we must conclude that every effect we see has to have a cause, and causes must exist for those causes, and so on forever. Yet the Scriptures explicitly reveal the Creator God, who made the world at a definite time. Rather than try to connect the overlapping answers of philosophy, theology and science, de Brabant held that philosophically the world was truly eternal, while theologically it was truly created by the Triune God. Deference must be given to matters of faith, to be sure, but truth could be philosophical in one way, and theological in another.

De Brabant and his students muted the belief of Double Truth in their official writings, but its influence remained. Their insistence on separate, at times contradictory truths, cut against the core value in Christendom that all truth is God’s, and therefore whole. The debates still continued regarding the usage of reason alongside faith. Unlike previous debates in the church which regarded reason as dangerous, but still useful for pursuing truth when correctly applied, reason was now regarded as separate from faith, with its own distinct truth. De Brabant and his students envisioned a schism between the tools of reason and the resources of faith. As this vision permeated the broader culture, it began to reshape Western civilization.

When this schism was at its worst, in an era of the Middle Ages now known as Scholasticism, some people resorted to radical moves to defend the faith from the overreach of reason. Though some had sought a happy synthesis between Aristotle and orthodoxy, later figures like William of Ockham saw only the corruptions of an ideology gone too far.

Ockham was aware of the triumphs of philosophy in the church, but mostly saw the tragedies it brought. One famous aspect of his work is commonly called Ockham’s Razor today. It is a philosophical principle by which one prefers the simpler of two otherwise equal explanations. Such a pragmatic principle reflects Ockham’s rather radical philosophical commitments. Rather than discuss abstract entities and obscure questions of Aristotle’s metaphysics, Ockham thought such intangible matters unreal and pernicious to a Christian’s faith. Who cares about the laws of nature? Isn’t God in control of all things? Why bother considering the form of a man’s soul when it is God who formed him without reference to some external, invisible Ideas?

Ockham’s problem with the scholastic age, and chiefly with Thomas Aquinas, was the conflating and mixing of the natural and the supernatural. Continuing the separation of previous philosophers, Ockham sought to undo past damage by demystifying nature and demystifying God. God is other, accessible only by the doctrines revealed by Scripture or the Church. Nature is here, able to be assessed, experienced, and manipulated by man’s observational and rational powers.

Ockham’s radical philosophy was governed by a theological disposition that reflected his Franciscan upbringing. Who can know the mind of the Almighty? How can mortal man presume to, as Aristotle thought, share in the intellect by which the universe was formed? There had been a corruption in the meaning of theology, according to Ockham. Theology was not studying God, nor thinking His thoughts after him. These were philosophical ambitions that denied God his majesty. Theology was listening and receiving the Word of God through his Scripture and the Church.

Ockham’s work was undoubtedly philosophical, but it was simultaneously an invective against the preceding era of Christendom, which sought to mix things that he believed must remain separate. In order to give proper reverence to God, we must keep our faith unsullied by the machinations of reason. Ockham wanted to return to a simpler age, to undo the present and restore a pre-scholastic past, where faith’s mysteries were treated as mysteries. But attempts to return to the past rarely end well, and Ockham’s attempts to remove philosophy from theology were unsuccessful in the face of a growing bifurcation between faith and reason, church and world, man and God.